Method for producing a semiconductor component

ABSTRACT

A method for producing a semiconductor component includes: providing a semiconductor body having a first dopant of a first conductivity type; forming a first trench in the semiconductor body starting from a first side; filling the first trench with a semiconductor filler material; forming a superjunction structure by introducing a second dopant of a second conductivity type into the semiconductor body, the semiconductor filler material being doped with the second dopant; forming a second trench in the semiconductor body starting from the first side; and forming a trench structure in the second trench.

TECHNICAL FIELD

The application relates to a method for producing a semiconductorcomponent.

BACKGROUND

In semiconductor components with field effect transistors in the reversevoltage range of from a few tens of volts to a few hundred volts, fieldplate trench field effect transistors are for example used. Improvementof the area-specific on-state resistance Ron×A is the subject of furtherdevelopment of such field effect transistors. In this case, for example,compromises are to be made in the required component properties, sincethe variation of one component parameter may have a different effect onthe component properties, for example may lead to an improvement in onecomponent property with a simultaneous deterioration of anothercomponent property. For example, an increase in the dopant concentrationin the drift zone may lead to a desired reduction of the area-specificon-state resistance Ron×A, but may entail an undesired reduction of thevoltage blocking ability between source and drain. Against thisbackground, this application relates to a method for producing a fieldeffect transistor with an improved specific on-state resistance Ron×A.

SUMMARY

The present disclosure relates to a method for producing a semiconductorcomponent. The method comprises provision of a semiconductor body, whichcomprises a first dopant of a first conductivity type. The method alsocomprises formation of a first trench in the semiconductor body as wellas filling of the first trench with a semiconductor filler material. Themethod furthermore comprises formation of a superjunction structure byintroducing a second dopant of a second conductivity type into thesemiconductor body, the semiconductor filler material being doped withthe second dopant. The method further comprises formation of a secondtrench in the semiconductor body as well as formation of a trenchstructure in the second trench.

Those skilled in the art will recognize additional features andadvantages upon reading the following detailed description, and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings serve for the understanding of exemplaryembodiments of the invention, are included in the disclosure and form apart thereof. The drawings merely illustrate exemplary embodiments andserve, together with the description, for the understanding thereof.Further exemplary embodiments and many of the intended advantages mayemerge directly from the detailed description below. The elements andstructures shown in the drawings are not necessarily representedtrue-to-scale with respect to one another. References which are the samerefer to elements and structures which are the same or correspond to oneanother.

FIG. 1 shows a schematic flowchart to illustrate an exemplary method forproducing a semiconductor component.

FIGS. 2A to 2K show schematic cross-sectional views of a semiconductorbody for exemplary illustration of method features in connection withthe flowchart of FIG. 1.

FIG. 3 shows a schematic flowchart to illustrate an exemplary method forproducing a semiconductor component.

FIGS. 4A to 4F show schematic cross-sectional views of a semiconductorbody for exemplary illustration of method features in connection withthe flowchart of FIG. 3.

FIGS. 5, 6A, 6B, 7 and 8 show respective schematic cross-sectional viewsof a semiconductor body for illustration of exemplary embodiments ofmethods for producing a semiconductor component.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part of this disclosure and in whichspecific embodiments are shown for illustration purposes. In thisregard, direction terminology such as “upper side”, “bottom”, “frontside”, “rear side”, “forward”, “backward”, “front”, “rear”, etc. refersto the alignment of the figures being described. Since the componentparts of exemplary embodiments may be positioned in differentorientations, the direction terminology serves only for explanation andis in no way to be regarded as limiting.

It is to be understood clearly that there are further exemplaryembodiments, and structural or logical modifications may be made to theexemplary embodiments without deviating from what is defined by thepatent claims. The description of the exemplary embodiments is to thisextent not limiting. In particular, elements of exemplary embodimentsdescribed below may be combined with elements of other of the exemplaryembodiments described, if the context does not dictate otherwise.

The terms “have”, “contain”, “comprise”, “include” and the like are openterms in what follows, which on the one hand indicate the presence ofthe elements or features mentioned, but on the other hand do not excludethe presence of further elements or features. The indefinite article andthe definite article encompass both the plural and singular, unless thecontext clearly dictates otherwise.

The term “electrically connected” describes a permanent low-ohmicconnection between electrically connected elements, for example directcontact between the relevant elements or a low-ohmic connection via ametal and/or a heavily doped semiconductor. The term “electricallycoupled” includes the possibility that there may be one or moreintermediate elements, which are suitable for signal transmission,between the electrically coupled elements, for example elements whichare controllable in order at different times to provide a low-ohmicconnection in a first state and high-ohmic electrical decoupling in asecond state.

Insulated gate field effect transistors (IGFETs) are voltage-controlledcomponents such as metal oxide semiconductor FETs (MOSFETs). The termMOSFET also includes FETs with gate electrodes based on dopedsemiconductor material and/or gate dielectrics which are not, or notexclusively, based on an oxide.

FIG. 1 represents a schematic flowchart 100 for the production of asemiconductor component according to one exemplary embodiment.

The flowchart 100 comprises method features which may respectively haveone or more processing steps. During production of the semiconductorcomponent, further processing steps may follow, for example before,between or alternatively after the method features shown. Likewise,further processing steps may be carried out between the processing stepsassigned to one method feature or alternatively together with theprocessing steps described. For example, a processing step, which isassigned to one method feature, of forming a trench by means of a mask,may comprise an etching process which forms both the trench describedand further trenches defined by means of the mask. Also, processingsteps of various method features may be carried out together or in adifferent order.

A method feature A10 comprises provision of a semiconductor body, whichcomprises a first dopant of a first conductivity type. The term “firstdopant of a first conductivity type” denotes a first dopant species of afirst conductivity type, for example boron for the case in which thefirst conductivity type is a p-type. The first dopant is present in thesemiconductor body as a multiplicity of individual elements of thedopant species of a first conductivity type, for example a multiplicityof boron atoms. Of course, the first conductivity type may also be ann-type, in which case phosphorus or arsenic represent exemplary dopantelements.

The semiconductor body may for example comprise a semiconductorsubstrate, for example a wafer of a monocrystalline semiconductormaterial, for instance silicon (Si), silicon-germanium (SiGe), siliconcarbide (SiC) or alternatively a III-V semiconductor material. Thesemiconductor material may furthermore comprise no, one or alternativelya plurality of semiconductor layers, which are for example formed on thesemiconductor substrate. The first dopant may for example be introducedinto the semiconductor body by ion implantation, by diffusion from adiffusion source or alternatively by in-situ doping during layerdeposition. Of course, a plurality of diffusion steps or alternativelyion implantation steps or alternatively a combination of diffusion andion implantation steps may respectively be used in order to introducethe first dopant. A depth distribution of the first and second dopantsmay, for example, be achieved by ion implantations with differentenergies, or alternatively by a method in which epitaxy and implantationalternate repeatedly (so-called “multi-epi/multi-implant” method).

A method feature A20 comprises formation of a first trench in thesemiconductor body starting from a first side. The first side may forexample be a front side of the semiconductor component to bemanufactured, for example the side on which a subsequent load terminal,such as a source terminal, and a subsequent control terminal, such as agate terminal, are formed. The first trench may for example be formedwith an etching process or a combination of a plurality of etchingprocesses, for example a physical dry etching method, a chemical dryetching method, a physicochemical dry etching method such as reactiveion etching (RIE) or alternatively a wet etching method. The etchingprocess may, for example, be carried out by means of aphotolithographically produced etching mask. Since the etching of thefirst trench is used for the subsequent formation of a superjunction(SJ), a depth of the first trench may for example be adjusted as afunction of a target voltage class of the semiconductor component to beachieved in the semiconductor body with the SJ structure.

A method feature A30 comprises filling of the first trench with asemiconductor filler material, for example carried out after the methodfeature A20. The semiconductor filler material may, for example, beproduced by a layer deposition method such as chemical vapor deposition(CVD). For example, the first trench is filled with the semiconductorfiller material by a method which allows filling with a maximally highcrystal quality, for example epitaxial growth of the side and bottomsurfaces of the first trench. A total dopant concentration in thesemiconductor filler material may, as an average value determined overthe vertical extent of the first trench, be more than two, or more thanthree or even more than four orders of magnitude less than acorresponding total dopant concentration in an area of the semiconductorbody located next to the first trench in relation to the same verticalextent. The semiconductor filler material may therefore be an intrinsicsemiconductor filler material, i.e. one which is doped only byimpurities but not deliberately, or a semiconductor filler materialwhich is deliberately lightly doped.

A method feature A40 comprises formation of a superjunction (SJ)structure by introducing a second dopant of a second conductivity typeinto the semiconductor body, the second dopant partially compensatingfor a concentration of the first dopant. The term “second dopant of asecond conductivity type” denotes a second dopant species of a secondconductivity type, for example phosphorus or arsenic for the case inwhich the second conductivity type is an n-type. The second dopant ispresent in the semiconductor body as a multiplicity of individualelements of the dopant species of the second conductivity type, forexample as a multiplicity of phosphorus atoms. Of course, the firstconductivity type may also be a p-type, in which case boron representsan exemplary dopant element.

The SJ structure is formed, by introducing the second dopant, in such away that the intrinsically or lightly doped semiconductor fillermaterial assumes the second conductivity type as a result of the dopingwith the second dopant, and the region of the semiconductor body whichsurrounds the semiconductor filler material and is of the firstconductivity type because of the first dopant is merely partiallycompensated for in doping by the doping with the second dopant or isprotected from partial compensation by a mask. If the semiconductorfiller material which is to with the second dopant is used as asubsequent drift zone of an SJ semiconductor component, in view of theat least partially lacking doping compensation in the semiconductorfiller material, there is improved charge mobility in comparison withthe surrounding region of the semiconductor body, since no scatteringtakes place on a dopant that merely leads to doping compensation. Thedoping compensation in the surrounding region is uncritical, however,since this region is not used for carrying the load current in thesubsequent semiconductor component, but is merely depleted of chargecarriers as a charge compensation region.

A method feature A50 comprises formation of a second trench in thesemiconductor body starting from the first side. The second trench mayfor example be formed, like the first trench, with one or a combinationof a plurality of etching processes, for example a physical dry etchingmethod, a chemical dry etching method, a physicochemical dry etchingmethod such as reactive ion etching (RIE) or alternatively a wet etchingmethod.

A method feature A60 comprises formation of a trench structure in thesecond trench. The formation of the trench structure may for examplecomprise the formation of a gate dielectric in the second trench, forexample by thermal oxidation and/or deposition of an oxide such as TEOS(tetraethyl orthosilicate), and also the formation of a gate electrodein the second trench, for example by deposition of doped polycrystallinesilicon. The trench structure may therefore, for example, be configuredas a gate trench structure of an IGFET.

The method according to the flowchart 100 makes it possible to produceSJ IGFETs of small lateral dimensions with moderate process complexity.Thus, the SJ structure may for example be dimensioned merely bylithographically defined trench etching, without having to resort tofurther lithographic levels for definition of the SJ structure in thecell field.

According to one exemplary embodiment, the first dopant is introducedinto the semiconductor body by a plurality of ion implantations withdifferent implantation energies or by in-situ doping. Ion implantationallows flexible configuration of a doping profile extending into thedepth of the semiconductor body by variation of energy and dose.

According to one exemplary embodiment, the first dopant is introducedinto the semiconductor body by a plurality of ion implantations withdifferent implantation energies, in such a way that a spacing of theneighboring implantation peaks in a vertical direction lies in a rangeof from 100 nm to 400 nm. In this way, as a result of the thermal budgetduring production of the semiconductor component, a waviness of thedoping profile along the vertical direction may be reduced or evenlargely suppressed.

According to one exemplary embodiment, a maximum implantation energy anda minimum implantation are selected in such a way that a verticalspacing of the associated implantation peaks lies in a range of from 1μm to 3 μm. This makes it possible, with a typical average dopingconcentration of from 10¹⁶ cm⁻³ to 5×10¹⁸ cm⁻³, to produce SJsemiconductor components in the voltage class range of from several tensof volts to a few hundred volts.

According to one exemplary embodiment, a non-doping element isintroduced into the semiconductor body in addition to the first dopant.The non-doping element is adapted to reduce diffusion of the firstdopant due to a thermal budget. This makes it possible to establish thelateral extent of the regions of the SJ structure by the dimensioning ofthe first trench. If boron is selected as the first dopant, for example,carbon as a non-doping element may for instance counteract diffusion ofthe boron and restrict a p-column of the SJ structure to a regionbetween neighboring first trenches. For example, carbon may beintroduced into the semiconductor body by in-situ doping, for exampletogether with the first dopant. As an alternative or in addition, carbonmay be introduced into the semiconductor body by one or more ionimplantations. Ion implantation allows flexible configuration of acarbon profile extending into the depth of the semiconductor body byvariation of energy and dose. Carbon may likewise be introduced into thesemiconductor body by one or more oblique implantations, for example byoblique implantations into side walls of the first trench before thefilling of the first trench. In this way, for example, a diffusionbarrier lining the first trench may be formed.

According to one exemplary embodiment, the second dopant is introducedfully, i.e. without masking, through a surface of an active transistorcell area by a plurality of ion implantations with differentimplantation energies. In this case, masking of the ion implantation maybe carried out, for example in a peripheral area adjacent to thetransistor cell area. Besides the second dopant, for example, carbon mayadditionally be introduced fully, i.e. without masking, through thesurface of an active transistor cell area by one or more plurality ofion implantations.

According to one exemplary embodiment, the first dopant is introducedfully, i.e. without masking, through a surface of an active transistorcell area by a plurality of ion implantations with differentimplantation energies. The SJ structure may therefore be establishedmerely by the dimensioning of the first trench, without the need for thefirst and second dopants, which form the SJ structure, to be introducedinto the transistor cell field with the masking. As in the case of theion implantations of the second dopant, masking of the ion implantation,for example in a peripheral area adjacent to the transistor cell area,may also be carried out during the ion implantation of the first dopant.

According to one exemplary embodiment, the superjunction structurecomprises a first region of the first conductivity type, in which thereis partial compensation for the doping of the first dopant by the seconddopant, and a neighboring second region of the second conductivity type,which comprises the semiconductor filler material and is doped with thesecond dopant, a dose of the first dopant measured along a segment,which passes fully through the first region and the second region in afirst lateral direction, differing by at most 5% from a dose of thesecond dopant along the same segment. The first lateral direction may inthis case, for example in a semiconductor component having strip-shapedgate structures/transistor cells, extend perpendicularly to thesestrips. The charges which are due to the first dopant and the seconddopant therefore cancel one another out approximately or even exactly.

According to one exemplary embodiment, a width of the second trenchalong the first lateral direction is less than a width of the secondregion along the first lateral direction. The semiconductor fillermaterial in the second region may therefore adjoin side walls of thesecond trench. This allows a reliable channel connection to a drift zoneduring subsequent formation of a gate structure in the second trench.

According to one exemplary embodiment, the formation of the trenchstructure comprises lining of the second trench with a dielectricstructure which is configured at least partially as a gate dielectric,as well as formation of a gate electrode material in the second trench.The second trench is therefore used to receive a gate dielectric and agate electrode. For example, the dielectric structure comprises athermally grown and special deposited oxide, which may form the gatedielectric or a part thereof. Exemplary gate electrode materials includeheavily doped semiconductor materials, for example polycrystallinesilicon, as well as metals or conductive metal compounds.

According to one exemplary embodiment, the formation of the secondtrench in the semiconductor body comprises a dry etching process, andsubsequently wet etching with an alkaline solution. The dry etchingprocess is for example a physical dry etching method, a chemical dryetching method, or alternatively a physicochemical dry etching methodsuch as reactive ion etching (RIE). The dry etching process may forexample be used for the trench formation, while the wet etching processwith an alkaline solution, for example an aqueous KOH or TMAH solution,is used to remove or reduce a taper, i.e. inclined trench side walls,formed during the dry etching. A perturbation of the charge balance inthe SJ structure by a taper during the formation of the first trench istherefore counteracted.

According to one exemplary embodiment, the semiconductor body isenlarged after filling of the first trench by forming a semiconductorlayer on the first side. The semiconductor layer may, for example, beadapted in terms of thickness and doping concentration to therequirements of a cell head above an SJ structure of the targetsemiconductor component.

According to one exemplary embodiment, a repetition of the methodfeatures A20, A30, A40 described in connection with FIG. 1 is carriedout. In this way, a vertical extent of the SJ structure can be achievedby means of multiple epitaxy, so that a restriction of the verticalextent of the SJ structure by the maximum energy during the ionimplantation can be overcome.

According to one exemplary embodiment, the second trench is formed lessdeeply into the semiconductor body than the first trench. The depthdifference corresponds, for example, to a desired vertical extent of theSJ structure below a gate trench.

The exemplary embodiments above may be combined with one another inorder to further refine the exemplary embodiment described withreference to FIG. 1.

Exemplary embodiments of a method for producing a semiconductorcomponent will be explained in more detail with reference to theschematic cross-sectional views of a semiconductor body in FIGS. 2A to2K.

With reference to the schematic cross-sectional view in FIG. 2A, asemiconductor body 102 is provided which comprises a first dopant of afirst conductivity type, for example boron. The semiconductor body 102comprises a semiconductor substrate 104, as well as a firstsemiconductor layer 106 formed on the semiconductor substrate 104. Thefirst semiconductor layer 106 may, for example, be formed by means of anepitaxial layer deposition method, for example chemical vapor deposition(CVD). The first dopant is, for example, present only in the firstsemiconductor layer 106. The first dopant may be introduced into thefirst semiconductor layer 106 of the semiconductor body 102 bothin-situ, i.e. during the layer deposition, or alternatively by aplurality of ion implantations with different energy after thedeposition of an e.g. intrinsic semiconductor layer. The firstsemiconductor layer 106 may also be constructed from a plurality ofsublayers, for example an optional base layer at the boundary with thesemiconductor substrate 104, a central layer into which the first dopantis introduced and which is used for the formation of an SJ structure, aswell as a component head layer on the central layer, which is used forexample to receive a component, which comprises for instance source andbody regions. The component head layer may, for instance, also bedefined in that, in a semiconductor layer deposited so that it isintrinsically or lightly doped, a lowest ion implantation energy forintroduction of the first dopant defines a boundary between the stillintrinsic or lightly doped component head layer and the central layer.

Besides the first dopant, a non-doping element, for example carbon, mayalso be introduced into the semiconductor layer 106 in order tocounteract subsequent lateral outward diffusion of the first dopant. Forexample, carbon may be introduced into the semiconductor layer 106 byin-situ doping and/or one or more ion implantations.

With reference to the schematic cross-sectional view in FIG. 2B, a firsttrench 108 is formed in the semiconductor body 102 starting from a firstside 110 by means of a mask 112, for example an etching mask. Theetching mask, for example a hard mask or a resist mask, may for examplebe formed by means of photolithographic structuring. The trench may, forexample, be formed by means of a dry etching process such as RIE, aswell as an optional wet etching process in an alkaline environment inorder to reduce or eliminate a taper. The bottom of the first trench 108ends, for example, at the transition to the semiconductor substrate 104,or alternatively inside the semiconductor layer 106 at a transition to abase layer. In order to counteract subsequent lateral outward diffusionof the first dopant, carbon may for example be introduced into thesemiconductor layer 106 by means of one or more oblique implantationsthrough side walls of the first trench 108. The introduction of carbonby means of oblique implantation(s) is illustrated by way of example inFIG. 2B by a dashed line.

With reference to the schematic cross-sectional view in FIG. 2C, thefirst trench 108 is filled with a semiconductor filler material 114. Thesemiconductor filler material 114 may, for example, be produced by meansof a layer deposition method such as chemical vapor deposition (CVD).For example, the first trench 108 is filled with the semiconductorfiller material 114 by a method such as selective epitaxy, selectiveepitaxy allowing filling with a maximally high crystal quality, forexample epitaxial growth on the side and bottom surfaces of the firsttrench 108. A total dopant concentration in the semiconductor fillermaterial may, as an average value determined over a vertical extent ofthe first trench 108, be more than two, or more than three or even morethan four orders of magnitude less than a total dopant concentrationdominated by the first dopant in an area of the semiconductor body 102located next to the first trench 108 in relation to the same verticalextent. The semiconductor filler material 114 may therefore be anintrinsic semiconductor filler material 114, i.e. one which is dopedonly by impurities but not deliberately, or a semiconductor fillermaterial 114 which is lightly doped.

With reference to the schematic cross-sectional view in FIG. 2D, themask 112 is removed and the semiconductor filler material 114 ispartially reduced, for example as far as a lower side of the mask 112.

Furthermore with reference to the schematic cross-sectional view in FIG.2D, a superjunction structure 128 is formed by introducing a seconddopant of a second conductivity type into the semiconductor body 102,the second dopant partially compensating for a concentration of thefirst dopant in a first region 116 between neighboring semiconductorfiller materials 114, and the semiconductor filler material 114 beingdoped with the second dopant. The SJ structure is therefore constructedfrom the semiconductor filler material 114, which has the secondconductivity type and represents a second region 117, and from the firstregion 116, which has the first conductivity type and partialcompensation of the doping. The first region 116 and the second region117 may, for example, be arranged alternately along the first lateraldirection.

According to one exemplary embodiment, a dose of the first dopant,measured along a segment AA′ passing fully through the first region 116and the second region 117 in a first lateral direction x, differs by atmost 5% from a dose of the second dopant along the same segment AA′. Thesegment AA′ is shown by way of example from the start of a column of thefirst dopant as far as the end of the column of the second dopant. Thesegment could equally well extend from half of a first column of thefirst dopant over the entire column of the second dopant and a furtherhalf of a column of the first dopant. The segment AA′ thus stands in arepresentative manner for a full period of the periodicity of thesuperjunction structure along the alternately doped columns.

According to the exemplary embodiment illustrated in FIG. 2D, the seconddopant is introduced into the semiconductor body by means of amultiplicity of ion implantations with different implantation energy.This is illustrated in FIG. 2D with the aid of arrows which end atdifferent depths of the semiconductor body 102. For example, the seconddopant is introduced into the semiconductor body 102 by a plurality ofion implantations with different implantation energies, in such a waythat a vertical spacing d, d2, d3 of the neighboring implantation peaksin a vertical direction y lies in a range of from 100 nm to 400 nm. Inthis case, the spacings d1, d2, d3 may be different, or alternativelypartially or entirely coincide. According to one exemplary embodiment, amaximum implantation energy and a minimum implantation energy areselected in such a way that a vertical spacing d of the associatedimplantation peaks lies in a range of from 1 μm to 3 μm. Theimplantation of the first dopant may, for example, be carried out withthe same number of implantations as the implantation of the seconddopant. Since the implantation energies for achieving a particularpenetration depth depend on the dopant species, these energies may forexample be adapted in such a way that the same penetration depths areachieved with the respective implantations.

According to the exemplary embodiment shown in FIG. 2D, the seconddopant is introduced fully, i.e. without masking, through a surface ofan active transistor cell area 118 by a plurality of ion implantationswith different implantation energies. In this case, masking of the ionimplantations may for example be carried out in a peripheral area 120laterally adjacent to the transistor cell area 118, for example by meansof a mask 122. Unmasked introduction of the second dopant in thetransistor cell area 118 and masking in the peripheral area 120 may beapplied in the same way to the introduction of the first dopant by ionimplantations. Besides the second dopant, for example, carbon mayadditionally be introduced fully, i.e. without masking, through thesurface of the active transistor cell area by one or more ionimplantations.

With reference to the schematic cross-sectional view in FIG. 2E a sourceregion 124 is formed in the semiconductor body 102, for example bymasked or unmasked ion implantation of a dopant of the secondconductivity type. Likewise, a body region 126 is formed in thesemiconductor body 102, for example by masked or unmasked ionimplantation of a dopant of the first conductivity type.

With reference to the schematic cross-sectional view in FIG. 2F a secondtrench 130 is formed in the semiconductor body 102 by means of aphotolithographically structured mask 132, for example an SiN mask, forexample by a dry etching method and/or wet etching method, such as forinstance described in connection with method feature A50 above. In thiscase, the second trench 130 extends less deeply into the semiconductorbody 102 than the first trench formed previously and filled with thesemiconductor filler material 114.

According to the exemplary embodiment represented in FIG. 2F, a width w1of the second trench 130 along the first lateral direction x is lessthan a width w2 of the second trench 117 along the first lateraldirection x. The semiconductor filler material 114 in the second region117 may therefore adjoin side walls of the second trench 130. Thisallows a reliable channel connection to a drift zone during subsequentformation of a gate electrode structure in the second trench 130.

With reference to the schematic cross-sectional view in FIG. 2G a trenchstructure 134 is formed in the second trench 130. The trench structure134 comprises a dielectric structure 136 as well as a gate electrodematerial 138, as for example explained above in connection with methodfeature A60.

With reference to the schematic cross-sectional view in FIG. 2H the mask132 is removed and a spacer 140 is formed, for example by layerdeposition such as oxide deposition and subsequent spacer etching. Theformation of the spacer 140 is followed by formation of a contact trench142, for example by means of a dry etching process and/or a wet etchingprocess. A heavily doped contact region 144 of the first conductivitytype may be formed at the bottom of the contact trench 142, in order toallow low-ohmic electrical connection of the body region to a contactmaterial.

With reference to the schematic cross-sectional view in FIG. 2I, acontact material 146 for electrical contacting of the body region 126 isformed in the contact trench 142 via the heavily doped contact region144, as well as for electrical contacting of the source region 124, andis continued as a wiring plane which, for example, may be structured ina further subsequent step.

Other conventional processing steps for manufacture of the semiconductorcomponent follow, for example formation of further electricallyinsulated and conductive structures on the first side 110, as well asformation of a backside contact.

Of course, the sequence of method steps as shown in FIGS. 2A to 2I mayalso be modified in order to obtain a further exemplary embodiment ofthe method according to FIG. 1.

For example, with reference to the schematic cross-sectional view inFIG. 2J, the formation of the SJ structure 128 as well as the formationof the second trench 130 may also be carried out already at the methodstage of FIG. 2C by the mask 112 being used as an implantation mark forintroduction of the second dopant and as a mask, for example as anetching mask, during formation of the second trench 130, cf. FIG. 2K.The formation of the second trench 130 may be followed by the methodsteps shown in FIGS. 2G to 2I. The formation of the source region 124 aswell as of the body region 126 may, for example, be carried out afterremoval of the mask 132 in FIG. 2G and before formation of the spacer140.

FIG. 3 represents a schematic flowchart 300 for the production of asemiconductor component according to one exemplary embodiment.

The flowchart 300 comprises method features which may respectively haveone or more processing steps. During the production of the semiconductorcomponent, further processing steps may follow, for example before,between or alternatively after the method features shown. Likewise,further processing steps may be carried out between the processing stepsassigned to one method feature or alternatively together with theprocessing steps described. For example, a processing step, which isassigned to one method feature, of forming a trench by means of a mask,may comprise an etching process which forms both the trench describedand further trenches defined by means of the mask. Also, processingsteps of various method features may be carried out together or in adifferent order.

The comments made in connection with the exemplary embodiments above,cf. for example FIG. 1, regarding structural elements or process stepsmay be applied to corresponding structural elements and process steps inconnection with the exemplary embodiments below.

A method feature B10 comprises formation of first trenches in asemiconductor body starting from a first side, a mesa region beingarranged between two neighboring trenches.

A method feature B20 comprises formation of a trench structure in thefirst trenches.

A method feature B30 comprises formation of a mask on the semiconductorbody on the first side.

A method feature B40 comprises implantation of a first dopant of thesecond conductivity type into the semiconductor body and through themesa region by means of the mask, the dopant being implanted as far as adepth below the trench structure.

A method feature B50 comprises a heat treatment of the semiconductorbody for lateral diffusion of the first dopant.

A method feature B60 comprises implantation of a second dopant of thefirst conductivity type into the semiconductor body and through the mesaregion by means of the mask, the dopant being implanted as far as adepth below the trench structure.

Both the first and the second dopants may, as is described in connectionwith the flowchart 100, be introduced into the semiconductor body by amultiplicity of implantations with different energy. The introduction ofthe first dopant and of the second dopant may be carried out through thesame mask.

Method features relating to the flowchart 300 will be explained in moredetail by way of example with the aid of the cross-sectional views in inFIGS. 4A to 4F.

With reference to the schematic cross-sectional view in FIG. 4A, firsttrenches 208 are formed in a semiconductor body 202 starting from afirst side 210, a mesa region 209 being arranged between two neighboringtrenches 208. The semiconductor body 202 comprises, for example, asemiconductor layer 206 on a semiconductor substrate 204. Thesemiconductor layer 206 is for example produced on the semiconductorsubstrate 204 by an epitaxial deposition method such as CVD, and is forexample less heavily doped than the semiconductor substrate 204. Theexemplary details indicated above in connection with method feature A10apply accordingly. A first mask 212, for example a SiN mask, is used forformation of the first trenches 208.

With reference to the schematic cross-sectional view in FIG. 4B, atrench structure 234 is formed in the first trenches 208. The trenchstructure 234 comprises a dielectric structure 236 as well as a gateelectrode material 238. The exemplary details indicated above inconnection with method feature A60 apply accordingly.

With reference to the schematic cross-sectional view in FIG. 4C, asecond mask 250 is formed on the semiconductor body 202 on the firstside 210. The second mask comprises for example silicate glass (SG), forexample BSG (borosilicate glass), TEOS (tetraethyl orthosilicate),polycrystalline or amorphous silicon, carbon or a combination thereof.According to one exemplary embodiment, the second mask 250 has an aspectratio of an opening 251 of more than 1:5, or even more than 1:10. Forexample, a thickness, i.e. a vertical extent dl, of the second mask 250is more than a thickness d2 of the semiconductor layer 206.

With reference to the schematic cross-sectional view in FIG. 4D, a firstdopant of the second conductivity type, for example phosphorus, isimplanted into the semiconductor body 202 and through the mesa region209 by means of the opening 251 in the second mask 250, the first dopantbeing implanted as far as a depth below the trench structure 234, forexample by a multiplicity of implantations with different energy, as isexplained in more detail above in connection with method feature A40 andis represented schematically in FIG. 2D. The first dopant is initiallypresent in a region 252 below the mesa region 209.

With reference to the schematic cross-sectional view in FIG. 4E, a heattreatment of the semiconductor body 202 for lateral diffusion of thefirst dopant is carried out. As a result of this, a widened region 252′of the second conductivity type is formed from the region 252.

With reference to the schematic cross-sectional view in FIG. 4F, asecond dopant of the first conductivity type, for example boron, isimplanted into the semiconductor body 202 and through the mesa region209 by means of the opening 251 in the second mask 250, the seconddopant being implanted as far as a depth below the trench structure 234,for example by a multiplicity of implantations with different energy, asis explained in more detail above in connection with method feature A40and is represented schematically in FIG. 2D. The second dopant defines afirst region 216 of an SJ structure 228, which region is of the firstconductivity type and experiences partial compensation of the dopingbecause of the first dopant of the second conductivity type present inthe first region 216. The first region 216 is adjoined by a secondregion 217, which lies in the widened region 252′ and is of the secondconductivity type. The first region 216 and the second region 217 formthe SJ structure 218 below a bottom of the trench structure 234.

In the first region 216, for example on average, for example averagedalong a lateral extent of the respective regions in the first lateraldirection x, there is a degree of doping compensation of the seconddopant by the first dopant which is greater than the degree ofcompensation of the first dopant by the second dopant in the secondregion 217.

The method stage shown in FIG. 4F is followed by further processes formanufacture of the semiconductor component, for example removal of thesecond mask 250 and removal of the first mask 212, as well as formationof a contact material for electrical contacting of the body region aswell as for electrical contacting of the source region, as explained forexample with the aid of the process steps illustrated in FIGS. 2H and2I.

FIG. 5 shows a further exemplary embodiment, in which the process stepsA10 to A40 are carried out in a modified form.

One exemplary embodiment of a method for producing a semiconductorcomponent comprises provision of a semiconductor body 302, whichcomprises a semiconductor layer 306 on a semiconductor substrate 304.The semiconductor layer 306 may consist of sublayers of differentconductivity type and/or dopant concentration, as is illustrated in FIG.5 by means of the two sublayers 3061, 3062, or alternatively of a singlesemiconductor layer which is deposited to be intrinsic or slightlydoped. Subdivision of the semiconductor layer 306 into sublayers ofdifferent conductivity type and/or dopant concentration allowsdeliberate influencing of the charge equilibrium of the SJ structure andshifting of the charge equilibrium to an excess of p-doping (so-calledp-loading) or n-doping (so-called n-loading) as a function of a depth inthe semiconductor substrate 306. The method furthermore comprisesformation of a trench 308 in the semiconductor body 302, for example bymeans of an etching mask 312, as well as lining of the trench 308 with asemiconductor lining layer 307 which comprises first dopants of a firstconductivity type and second dopants of a second conductivity type. Themethod furthermore comprises filling of the trench with a semiconductorfiller material 314, which is arranged between a first side wall section355 and a second side wall section 356 of the semiconductor lininglayer, as well as formation of a superjunction layer by introducing someof the first dopants from the first and second side wall sections 355,356 of the semiconductor lining layer 307 into the semiconductor fillermaterial 314.

By different diffusion of the first and second dopants from thesemiconductor lining layer into the filling material, which results forexample from different penetration depths/penetration rates of the firstand second dopants for the same thermal budget, a superjunctionstructure may be configured with alternately doped columns lying closeto one another. The semiconductor body may be constructed from aplurality of sublayers before the diffusion step, the sublayer 3061 forexample having a low concentration of the first dopant and the secondsublayer 3062 having a low concentration of the second dopant, andtherefore form a trapezoidal net doping profile.

According to one exemplary embodiment, the method furthermore comprisesformation of a first trench gate structure and a second trench gatestructure above the superjunction structure, the first trench gatestructure overlapping with a vertical extension of the first side wallsection, and the second trench gate structure overlapping with avertical extension of the second side wall section. In this way,effective pitch doubling may be achieved.

According to one exemplary embodiment, a lateral center-to-centerspacing between the first side wall section and the second side wallsection coincides with a lateral center-to-center spacing between thefirst trench gate structure and the second trench gate structure.

According to one exemplary embodiment, the semiconductor body providedcomprises a doped semiconductor substrate and, thereon, a semiconductorlayer stack which is doped more lightly compared with the semiconductorsubstrate, and the trench is formed through the semiconductor layerstack at least as far as the semiconductor substrate.

According to one exemplary embodiment, the first dopants correspond toboron and the second dopants correspond to arsenic.

According to one exemplary embodiment, the semiconductor component isformed as a field effect transistor having a channel conductivity of thesecond conductivity type.

According to one exemplary embodiment, the semiconductor layer stackcomprises a first semiconductor layer of the first conductivity type anda second semiconductor layer of the second conductivity type.

According to one exemplary embodiment, after the filling of the trenchwith the semiconductor filler material, at least one third semiconductorlayer is formed on the semiconductor body, and a source region and abody region are formed in the third semiconductor layer.

According to one exemplary embodiment, a diffusion coefficient of thefirst dopants in the semiconductor body is greater than a diffusioncoefficient of the second dopants in the semiconductor body, and theformation of the superjunction structure comprises a thermal diffusionprocess by which more first than second dopants diffuse from the firstand second side wall sections into the semiconductor filler material, sothat the semiconductor filler material is at least partially of thefirst conductivity type and the first and second side wall sections areat least partially of the second conductivity type.

According to one exemplary embodiment, a dose, introduced into thesemiconductor lining layer, of the first dopants differs by at most 5%from a dose, introduced into the first semiconductor layer, of seconddopants.

According to one exemplary embodiment, the first and the second dopantsare introduced into the semiconductor lining layer by means of in-situdoping.

According to one exemplary embodiment, an aspect ratio of the trenchlies in a range of from 1:2 to 1:10.

According to one exemplary embodiment, a depth of the trench lies in arange of from 1 μm to 5 μm.

According to one exemplary embodiment, an in-situ dopant concentrationof the semiconductor filler material is at least two orders of magnitudeless than an in-situ dopant concentration of the second dopants in thesemiconductor lining layer.

According to one exemplary embodiment, the semiconductor lining layer isremoved from a part of the bottom of the trench.

One exemplary embodiment of a semiconductor component comprises a firstand a second trench gate structure, which extend from a first surfaceinto a semiconductor body. The semiconductor component furthermorecomprises a superjunction structure, a vertical extension of a mesaregion between the first trench gate structure and the second trenchgate structure overlapping at least partially with a first superjunctionsemiconductor region of a first conductivity type, and verticalextensions of the first gate structure and of the second gate structurerespectively overlapping at least partially with a second superjunctionsemiconductor region of a second conductivity type, the first and secondsuperjunction semiconductor regions being arranged alternately along alateral direction. The first superjunction semiconductor regioncomprises first dopants of the first conductivity type and seconddopants of the second conductivity type, the first dopants partiallycompensating for the second dopants, and a dopant concentration profileof the first dopants along the lateral direction having a maximum in amiddle of the second superjunction semiconductor region.

According to one exemplary embodiment, the first and second dopantscorrespond to one of the pairs boron and arsenic, boron and antimony,gallium and arsenic, gallium and antimony.

According to one exemplary embodiment, the first superjunctionsemiconductor region is electrically connected by means of a body regionof the first conductivity type to the first surface, and thesuperjunction semiconductor region of the second conductivity type iselectrically connected by means of a drift zone of the secondconductivity type to a second surface, lying opposite the first surface,of the semiconductor body.

According to one exemplary embodiment, a dopant concentration profile ofthe second dopants along the lateral direction has a maximum in themiddle of the second superjunction semiconductor region.

According to one exemplary embodiment, a dopant concentration profile ofthe first dopants along the lateral direction has a minimum in a middleof the first superjunction semiconductor region.

According to one exemplary embodiment, a dopant concentration profile ofthe first dopants along the lateral direction at a pn junction betweenthe first superjunction semiconductor region and the secondsuperjunction semiconductor region decreases from the secondsuperjunction semiconductor region to the first superjunctionsemiconductor region.

As an alternative to the method described in FIG. 5, the dopants mayalso be brought into the edge areas of the trench by means of stepwiseimplantation. The introduction of the semiconductor lining layer 307 ofFIG. 5 accordingly brought about by implantation of dopants of the firstand second types at the side edge of the trenches, as can be seen inFIGS. 6A and 6B in the form of the implanted doped regions 358. In thiscase, the doped regions 358 are stacked in a vertical direction by asuccession of implantations and deepenings of the trench 308. During thedeepening of the trench 308, for example carried out by one or moreetching steps, some of the dopants previously introduced by implantationare removed again.

The trench may subsequently be filled with filler material 314, forexample with undoped silicon, and a superjunction structure havingalternately doped columns lying close to one another may be formed bythermal diffusion.

One exemplary embodiment comprises a method for producing asemiconductor component. The method comprises provision of asemiconductor body, which comprises a trench, a first semiconductor bodyarea respectively being formed on opposite side walls of the trench. Thefirst semiconductor body area comprises first dopants of a firstconductivity type and second dopants of a second conductivity type, in ahigher concentration than in a second semiconductor body area laterallyadjacent to the first semiconductor body area. The method furthermorecomprises filling of the first trench with a semiconductor fillermaterial, which is arranged between the opposite side walls of thetrench. The method furthermore comprises formation of a superjunctionstructure by introducing some of the first dopants from the firstsemiconductor body area into the semiconductor filler material.

According to one exemplary embodiment, the provision of thesemiconductor body comprises:

-   -   i) formation of a mask having a mask opening on the        semiconductor body;    -   ii) introduction of the first dopants into the semiconductor        body through the mask opening;    -   iii) introduction of the second dopants into the semiconductor        body through the mask opening;    -   iv) formation of a recess in the semiconductor body below the        mask opening;    -   v) repetition of steps ii) to iv) at least once, so that the        trench is formed by the recesses and the first semiconductor        body area is bounded by the introduced first and second dopants.

According to one exemplary embodiment, after step i) and before stepii), the method furthermore comprises formation of a trench in thesemiconductor body below the mask opening, as well as filling of thetrench with a filler. This exemplary embodiment is represented by way ofexample in the schematic cross-sectional view in FIG. 7, the fillerbeing denoted by the reference 359. A material of the filler may, forexample, the selected with a view to precise formation of the recessesby an etching process.

According to one exemplary embodiment, the filler comprises one or moreof the materials resist, oxide, silicon nitride, epitaxial or amorphoussilicon-germanium, carbon, oxide lining of the trench with amorphous orpolycrystalline silicon filler.

According to one exemplary embodiment, the first dopants and the seconddopants are introduced into the semiconductor body by an ionimplantation process.

According to one exemplary embodiment, an implantation dose of the firstdopants differs by at most 5% from an implantation dose of the seconddopants.

One exemplary embodiment of a method for producing a semiconductorcomponent comprises provision of a semiconductor body which comprises atrench, a first semiconductor body area respectively being formed onopposite side walls of the trench, which area comprises first dopants ofa first conductivity type and second dopants of a second conductivitytype, in a higher concentration than in a second semiconductor body arealaterally adjacent to the first semiconductor body area. The methodfurthermore comprises filling of the first trench with a semiconductorfiller material, which is arranged between the opposite side walls ofthe trench, as well as formation of a superjunction structure byintroducing some of the first dopants from the first semiconductor bodyarea into the semiconductor filler material.

It is furthermore possible to combine the possibilities presented abovefor the formation of the superjunction structure. For example, theintroduction of dopants through the trench, as shown in FIG. 6A, may berestricted to dopants of one type, for example of the first type. Afterthe filling of the trench with undoped semiconductor material, forexample silicone, subsequent implantation of the second dopant may becarried out over the entire surface, as is shown in FIG. 8. Theimplantation may be carried out through a scattering layer 360, forexample a scattering oxide.

Other processing steps for manufacture of the semiconductor componentfollow, for example formation of a semiconductor component head layer,method features A50, A60, formation of further electrically insulatingand conductive structures on the first side, as well as formation of abackside contact.

Although specific embodiments have been illustrated and describedherein, persons skilled in the art will understand that the specificembodiments shown and described may be replaced by many alternativeand/or equivalent configurations, without departing from the protectivescope of the invention. The application is intended to include anyadaptations or variants of the specific embodiments discussed herein.The invention is therefore restricted only by the claims and theirequivalents.

What is claimed is:
 1. A method for producing a semiconductor component,the method comprising: providing a semiconductor body having a firstdopant of a first conductivity type; forming a first trench in thesemiconductor body starting from a first side; filling the first trenchwith a semiconductor filler material; forming a superjunction structureby introducing a second dopant of a second conductivity type into thesemiconductor body, the semiconductor filler material being doped withthe second dopant; forming a second trench in the semiconductor bodystarting from the first side; and forming a trench structure in thesecond trench, wherein forming the trench structure comprises: liningthe second trench with a dielectric structure which is configured atleast partially as a gate dielectric; and forming a gate electrodematerial in the second trench.
 2. The method of claim 1, wherein thesecond dopant partially compensates for a concentration of the firstdopant.
 3. The method of claim 1, wherein the first dopant is introducedinto the semiconductor body by a plurality of ion implantations withdifferent implantation energies or by in-situ doping.
 4. The method ofclaim 3, wherein the first dopant is introduced into the semiconductorbody by the plurality of ion implantations with different implantationenergies, such that a spacing of neighboring implantation peaks in avertical direction lies in a range of 100 nm to 400 nm.
 5. The method ofclaim 3, wherein a maximum implantation energy and a minimumimplantation are selected such that a vertical spacing of the associatedimplantation peaks lies in a range of 1 μm to 3 μm.
 6. The method ofclaim 3, further comprising: introducing a non-doping element into thesemiconductor body in addition to the first dopant, the non-dopingelement being configured to reduce diffusion of the first dopant due toa thermal budget.
 7. The method of claim 6, wherein the non-dopingelement is carbon.
 8. The method of claim 7, wherein the carbon isintroduced into the semiconductor body by in-situ doping or by one ormore ion implantations.
 9. The method of claim 1, wherein the seconddopant is introduced fully without masking, through a surface of anactive transistor cell area by a plurality of ion implantations withdifferent implantation energies.
 10. The method of claim 1, wherein thefirst dopant is introduced fully without masking, through a surface ofan active transistor cell area by a plurality of ion implantations withdifferent implantation energies.
 11. The method of claim 1, furthercomprising: introducing carbon fully without masking, through a surfaceof an active transistor cell area by one or more ion implantations. 12.The method of claim 1, wherein the superjunction structure comprises afirst region of the first conductivity type, in which there is partialcompensation for the doping of the first dopant by the second dopant,and a neighboring second region of the second conductivity type, whichcomprises the semiconductor filler material and is doped with the seconddopant, and wherein a dose of the first dopant along a segment differsby at most 5% from a dose of the second dopant along the same segment,the segment passing fully through the first region and the second regionin a first lateral direction.
 13. The method of claim 12, wherein awidth of the second trench along the first lateral direction is lessthan a width of the second region along the first lateral direction. 14.The method of claim 1, wherein forming the second trench in thesemiconductor body comprises: a dry etching process; and after the dryetching process, wet etching with an alkaline solution.
 15. The methodof claim 1, further comprising: enlarging the semiconductor body byforming a semiconductor layer on the first side after filling the firsttrench.
 16. The method of claim 1, wherein the second trench is formedless deeply into the semiconductor body than the first trench.
 17. Amethod for producing a semiconductor component, the method comprising:providing a semiconductor body having a first dopant of a firstconductivity type; forming a first trench in the semiconductor bodystarting from a first side; filling the first trench with asemiconductor filler material; forming a superjunction structure byintroducing a second dopant of a second conductivity type into thesemiconductor body, the semiconductor filler material being doped withthe second dopant; forming a second trench in the semiconductor bodystarting from the first side; and forming a trench structure in thesecond trench, wherein the first dopant is introduced into thesemiconductor body by a plurality of ion implantations with differentimplantation energies, wherein a spacing of neighboring implantationpeaks in a vertical direction lies in a range of 100 nm to 400 nm and/ora maximum implantation energy and a minimum implantation energy areselected such that a vertical spacing of the associated implantationpeaks lies in a range of 1 μm to 3 μm.
 18. A method for producing asemiconductor component, the method comprising: providing asemiconductor body having a first dopant of a first conductivity type;forming a first trench in the semiconductor body starting from a firstside; filling the first trench with a semiconductor filler material;forming a superjunction structure by introducing a second dopant of asecond conductivity type into the semiconductor body, the semiconductorfiller material being doped with the second dopant; forming a secondtrench in the semiconductor body starting from the first side; andforming a trench structure in the second trench, wherein at least one ofthe first dopant and the second dopant is introduced fully withoutmasking, through a surface of an active transistor cell area by aplurality of ion implantations with different implantation energies. 19.A method for producing a semiconductor component, the method comprising:providing a semiconductor body having a first dopant of a firstconductivity type; forming a first trench in the semiconductor bodystarting from a first side; filling the first trench with asemiconductor filler material; forming a superjunction structure byintroducing a second dopant of a second conductivity type into thesemiconductor body, the semiconductor filler material being doped withthe second dopant; forming a second trench in the semiconductor bodystarting from the first side; forming a trench structure in the secondtrench; and introducing carbon fully without masking, through a surfaceof an active transistor cell area by one or more ion implantations. 20.A method for producing a semiconductor component, the method comprising:providing a semiconductor body having a first dopant of a firstconductivity type; forming a first trench in the semiconductor bodystarting from a first side; filling the first trench with asemiconductor filler material; forming a superjunction structure byintroducing a second dopant of a second conductivity type into thesemiconductor body, the semiconductor filler material being doped withthe second dopant; forming a second trench in the semiconductor bodystarting from the first side; and forming a trench structure in thesecond trench, wherein the superjunction structure comprises a firstregion of the first conductivity type, in which there is partialcompensation for the doping of the first dopant by the second dopant,and a neighboring second region of the second conductivity type, whichcomprises the semiconductor filler material and is doped with the seconddopant, wherein a dose of the first dopant along a segment differs by atmost 5% from a dose of the second dopant along the same segment, thesegment passing fully through the first region and the second region ina first lateral direction.
 21. The method of claim 20, wherein a widthof the second trench along the first lateral direction is less than awidth of the second region along the first lateral direction.